Various ventilator and respirators have been provided. However, they have been deficient in that they have failed to provide an adjustable post-inspiratory flow. In the past, when post-inspiratory flow was developed by locking up the proximal airway in a static state, many subjects developed varying degrees of dyspnea. There is, therefore, a need for a new and improved ventilator and method which provides an adjustable post-inspiratory apneustic plateau flow for a period of time which does not have the above named disadvantages.